Hi, I am texturing my model at the moment, however I have ran into trouble resizing textures. is there any method in which I can resize?
You typically leave the uv mapping alone, but drill into the material to the texture and set tweak the settings there right in the materials panel.
As it says in the yellow dialog - your texture uses WCS mapping which means it completely ignores the mapping panel. The only way to change its size is to go into the texture inside the material itself and change the size there:
Note that with this method, all objects that have this texture assigned will show the texture with the same scale AND orientation. This might not be what you always want, eg. if you have wood texture where you want to control the direction of the grain. In that case you can click the “fix automatically” text in the yellow dialog after which you can apply whatever mapping you want to individual objects even if they have the same material. You can emulate the WCS with box mapping but you can then change orientation of the mapping box for a particular object if you need. Or use a different offset or scale if desired. The caveat is that the scale of the texture then generally changes with the scale of the object so you might need to edit the mapping every time after such operation.
Indeed with WCS/OCS (box or not) it does not matter what UV mapping you do. But if you were to set the texture to use a mapping channel you can control it a bit more. It really depends on what our needs are, as you have found out.